<!DOCTYPE html>
<html>
<body>

<p>Example list:</p>

<ul><li id="item1">Coffee (first li)</li><li id="item2">Tea (second li)</li></ul>

<p>Click the button to get the HTML content of the previous sibling of the second list item.</p>

<button onclick="myFunction()">Try it</button>

<p><strong>Note:</strong> Whitespace inside elements is considered as text, and text 
is considered as nodes.</p>

<p>If you add whitespace between the two li elements, the result will be "undefined".</p>

<p id="demo"></p>

<script>
function myFunction() {
  var x = document.getElementById("item2").previousSibling.innerHTML; 
  window.alert(x);
}
</script>

</body>
</html>